#练习1：从键盘中输入任意一串数字，统计“a”出现的次数

# str1 = "建设银行123"
#
# for i in str1:
#     print(i)

input_string = input("请从键盘进行输入：")

count_a = 0
for i in input_string:
    if i == 'a':
        count_a += 1

print("a出现的次数为：%d" % count_a)






